text:
Can heat from the engine inlet be used to produce thrust?
As the engine inlet temperature increases, Is more heat energy provided by air?
if yes then can we utilize that heat energy to produce more thrust?

I am not exactly sure what you mean? Are you talking about the ambient temperature of the air?

Are you talking about temperature increasing simply due to warmer weather, or due to compression heating at higher speed? (The answer is no in both cases, but for slightly different reasons).

I guess the heat you ask about is the temperature increase that goes with the precompression of air ahead of and in the intake. This heat is further increased in the compressor, according to the ideal gas law. If there were no temperature increase during compression, the engine could burn a lot more fuel and produce a lot more thrust.
To use the precompression heat would mean that first the air flows through a heat exchanger in order to transfer that heat to something that can produce thrust from it. That something would have to heat the air in the combustion chamber or after the last turbine stage in order to increase thrust. At both stations the gas temperature is a lot higher than the heat that can be harvested from the intake air. Now you first have to run that heat through a heat pump to make it useable (or, if you turn this around, you need a heat pump to produce a medium cold enough to harvest heat from the intake air in the first place!).
I hope you start to see how much more complicated and heavy this kind of engine will become. There have been attempts to recuperate the heat of the exhaust flow in turboprops, but so far nothing of that kind has ever entered production.

I suppose that is what happens with the compression process on a ramjet or scramjet.

Heat is an unfortunate and unavoidable by-product of energy conversion. Some of it can be transformed into propulsive energy: the steam engine, steam turbine and Sterling engine do this. Another way that heat energy can be transformed into propulsive energy is by injecting water in the hot stream: if that stream is hot enough the water droplets transform into vapour within the engine, and that provides thrust.
Having said that, gas turbines have pretty high efficiency at full power output, in the order of 40%. That means that 60% is waisted as heat - in some power stations the waste heat is used to power a steam turbine, raising the total efficiency to over 60%. A bit of a heavy set-up for an aircraft though..


text:
Is there a website with a list of all commercial airline incidents?
I am looking for a website that contains a listing of all commercial airline incidents (under a sufficiently large definition of "incident"), by airline company.
I assume that incidents that happen are logged automatically somewhere, and I presume that this information may be further relayed to a public website.

Here's my finding so far:
I know of the ASRS database, https://asrs.arc.nasa.gov/search/dbol/strategies.html, but this doesn't list airline names, as far as I could see (and is also tricky to navigate).
The 3 other more usable website, that don't report just accidents, but also incidents (whatever they define as "incident"... meaning sites like http://aviation.globalincidentmap.com/ are excluded) are
https://aviation-safety.net/
http://avherald.com/
https://www.aeroinside.com/
Are these sources credible?
E.g. http://avherald.com/ states in their FAQ that they compile their report based on "own sources". https://www.aeroinside.com/ says, after some looking, that it's information is compiled from multiple other databases, but doesn't specify which. https://aviation-safety.net/ seems the most legit of these (excepting ASRS), but again, official assurances are missing.
I'm asking this, because I'd like to compile for myself some flights statistics (I'm a statistician by profession) and I'd like some site sthat are easier to navigate than ASRS (recompiling their data in a form amenable to statistics would be very time-consuming).

Please define the scope of your interest. Are you interested in US carriers, European, US & European, Global? If Global, good luck, there is no global database of incidents.

Related meta question

@CGCampbell I'm interested in European carriers flying to Asia resp. vice versa, Asian carriers flying to Europe.

Each jurisdiction or organization will have its own reporting system, not all will provide that information to the public. News, social media, and websites provide information but more research is required to determine which parts are accurate.
https://aviation-safety.net/
The Aviation Safety Network is probably your best bet for both completeness and accuracy. The database is fairly comprehensive, contains events as far back as 1919, and lists sources. You can browse by date, location, and aircraft type. The Wikibase allows users to add incidents, providing coverage of many more small aircraft incidents but may be less accurate.
https://avherald.com/
Avherald strives for accuracy but is far from complete. Information is not reported without reasonable verification, sources are provided when possible. The team sometimes even has access to the radar data to provide more insight. Many news outlets use this as a source. Entries go as far back as 1999, but the items are intended to provide information on accidents and an overview of the types of incidents occurring worldwide. This will make any statistical analysis hard.
https://www.aeroinside.com/
AeroInside appears to just copy from Avherald and put the entries in a fancier format with ads and make them a bit more searchable.

This is good info. As soon as I'll have 15 rep points to upvote, I'll do that.

under a sufficiently large definition of "incident"

Although somewhat vague, ICAO and most national regulatory agencies do have an actual definition for the term "Incident". First, however, you need to start with the term, "Accident", which can get very specific... down to the number of days someone was hospitalized, or a certain monetary damage amount, for example. Then, the definition of incident becomes, essentially, "anything that does not meet the definition of an accident, but which the safety of operations was or could have been affected."
Source: ICAO Annex 13; US NTSB Part 830.2

I assume that incidents that happen are logged automatically somewhere

Although I can only speak for the US, Part 830 defines what an incident is and which ones must be reported, by whom, and when.  These incidents are recorded in the online NTSB database, and can be retrieved in several formats conducive to statistical analysis (xml, csv, etc.).
https://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx
There are non-US accidents/incidents also in this database if US parts or aircraft were involved (a Boeing 737, an engine part manufactured in the US, etc.); however, these aren't as readily formatted for statistical analysis - but they do point to the foreign nation's investigative board's information.

Unfortunately I don't have 15 rep to be able to upvote this, as this gives a perfect answer regarding US carriers.

There is also JACDEC (Jet Airliner Crash Data Evaluation Centre).
JADEC provide, for each airline listed, a "safety index".
The Index is the result of a complex formular containing multiple factors such as accidents and serious incidents, revenue passenger numbers, Safety Audits, etc.
The safety index for each airline they cover is shown on their website. Unfortunately, if you want the report that comes up with that assessment, I believe you have to pay for it.
Also, a subtle point,  JADEC is NOT a list of airlines in order of safety. Its a list of the 60 biggest airlines (in terms of revenue), in order of safety.
The Safety Index is calculated from a number of factors. They say:

We believe the operational environment is a crucial factor for an airline´s safety performance.
  One lesson of our now decade-long experience in aviation safety analysis is the following: There is a direct correlation between the safety of a airline and the competence and transparency of the controlling authorities.
  Therefore we use for years the results of the so-called USOAP , this abbreviation stands for Universal Safety Oversight Audit Programme . In this global program, guided by all ICAO member, the whole civil aviation system is undergoing a voluntary audit. In particular it is investigated how a country is able to meet and maintain defined standards on aviation safety.
Furthermore, we looked at the level of trancparency an governing authority has. We ask: Are there all relevant occurences laid on the table, or not ? Compared to earlier years, 2013 gave us some encouraging results, but many important players like China, Turkey or Mexico failed to open their accident investigations to a wider audience.

It's prehaps not what your loking for, because you want the raw data to make your own assessments/analysis, rather than someone elses's that includes non-statistical factors, but it seems to be quite a reputable and robust / professional assessment.

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text:
Would a slower and larger rotor blade be practical?
Essentially a rotor is a rotating wing and the design of that wing generates lift. My question is this, why not increase the surface area of the rotor and slowdown the rotor speed. Rotor strength will also be increased. Slower rotor speeds will also reduce the turbulence created by the larger area of the rotor.
I believe that this will also increase efficiency as the reduced speed can result in smaller engines being used to do the same work.

It's just hard to make long and strong blades. And rotor speed has its own limit, too, which leaves the only option to be adding more blades. No one want to make a 20 blade rotor if they could get away with 2, yet you still see a lot of 5 blade helicopters.

Indeed a relatively large rotor has advantages:

Low induced velocities: less sand and bushes that are swept up by the rotor airstream.
Low autorotational rate of descent.
Low power required in the hover.

However, there are some disadvantages as well:

The size of the helicopter is less practical at landing, take-off, clearance of buildings etc.
The empty weight is higher, a very important factor in VTOL aircraft.
The hub drag is higher.

A smaller rotor will have a smaller and lighter hub and a lower overall parasitic drag: more efficient for cruising flight. There is a practical limit to blade radius of about 12 m due to static rotor droop when not spinning. From J. Gordon Leishman:

The static droop can increase quickly for larger rotor diameters and may cause problems when starting and stopping the rotor, especially in gusty wind conditions where the low centrifugal forces on the blades may lead to "blade sailing,"causing the rotor blades to flap and flex and perhaps impact the airframe.

The rotational speed of the rotor is determined by the tip speed, and is set such that at cruise speed the advancing blade tip stays below the drag divergence Mach number. Reducing the tip speed permits a higher flight speed to be achieved.
Image source
There is a design optimum for rotor disk size, determined by weight. The weight over disk area ratio is the disk loading and the analogy with wing loading of fixed wing aircraft is very strong: a large wing area creates more drag and construction weight. The relationship between disk loading and operating weight is partly governed by the square-cube law, and a clear trend can be observed when the two parameters are plotted against each other: there is an optimum governed by weight, and the optimum is not the largest rotor diameter.

Rogers says,

Theoretically the most efficient propeller is a large diameter, slowly turning single blade propeller.

Generally, all else being equal, if you can get a larger-diameter propeller or fan on your aircraft, you will have greater efficiency. We see turbofans getting bigger and bigger and bigger partially for this reason. It also underscores why the AeroVelo Atlas has such large rotors.
So why not just stick giant props on everything? There are many factors, including

The practicality of manufacture. Can you build blades long enough and stiff enough without negating your extra efficiency with weight?
The arrangement of the aircraft. Can you fit the prop under the wing, for example? Or for a helicopter, will the blades have enough ground clearance at their tips when the rotor isn't spinning?
The intended airspeed of the aircraft. As Airsick mentions in a comment, on a helicopter you might get very little forward speed before stalling part of the blade. On a fixed-wing airplane, you'll more quickly run into supersonic flow at the blade tips (which causes unacceptable drag and noise) as you try to spin the propellor faster.

Any aircraft design is the result of rigorous and extensive trade-offs and optimizations. The points you make are valid, but they are usually constrained by other factors.

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text:
Y force of airplane in ground effect
How can I get the y force of an airplane in ground effect when using image theory? is the y force zero because of the mirror cancelling it out? bare in mind I'm talking about a case where there is a sideslip angle.
Many thanks

Ground effect happens because the air cannot flow around the airplane as it would in free flight. The impenetrable ground gets in the way, and using the mirror image in CFD is done only to create an opposing flow field so the direction of flow in the ground plane (= plane of symmetry for the mirror image) will always be horizontal.
In order to create lift, the airplane is adding a vertical speed component to the air and ground effect is the consequence of a restricted vertical movement for this air. In order to create a side force, air would need to have a horizontal speed component added, orthogonal to the direction of the initial flow speed. Since there is nothing which restricts this horizontal movement, the flow pattern will not really differ from free flight, and so should the forces.

The mirror image won't cancel it out.
To a first order, I would assume it is unaffected.  I haven't ever run a detailed analysis to see if there was an effect, but I would be surprised to see one that wasn't very small and configuration dependent.  I.e. I doubt a general statement can be made about trends and magnitude.
Any aero tool that can model a ground effect should be able to answer this question for you with a little experimentation.

Thank you for your reply. Does that mean (side force in ground effect - side force out of ground effect) = 0 (or approx 0)?

I would think so, yes.

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text:
Is there any way to bring down a large spy balloon without force?
This might seem like a silly question, but I mean it.
A Chinese spy balloon recently flew over the US and was taken down with a missile. Apparently, it was very important to recover its payload safely, but a nearby missile detonation, a long fall and a few days on the ocean floor will likely have damaged most of the payload.
My question is: Wasn't there a way to bring down the balloon without force? I am imagining something like flying a balloon next to it to grab the payload, or a large net. This way the payload would be recovered intact, without creating risk for civilians at ground level.
Why aren't these feasible options, or, if they are, why shoot it down?

Someone else asked a similar question: Why use a missile instead of a rotary gun? However, I am specifically curious if there is any way to non-destructively bring such a balloon down.

Related - https://aviation.stackexchange.com/questions/97499/could-the-us-military-have-harnessed-the-chinese-observation-balloon-and-accesse

A pair of US Army airships with some rigging between them could capture a balloon.  However, they were retired in 1937.

Too bad it was so high up, maybe they could have used this approach ;) https://www.youtube.com/watch?v=oY-pdk_FWh0

Your suggestions may be entirely feasible, but they would need to be engineered, tested, built, and then deployed to the areas where they might be needed.  Crews to operate these systems would need to be recruited and trained.  All this takes time, and money.
Resources are allocated and projects are scoped to meet requirements established to fill a need.  Since there haven't been a sufficiently large number of balloon incursions threatening us in the past, demand for such a recovery system has been low.  Therefore no tax dollars have been spent to create a federal balloon recovery infrastructure.
That’s probably a wise decision from a cost benefit standpoint, even when compared to a pricy missile.

The balloon was far too high to just tow down. And by then, it may be in international airspace, which would stop the US from capturing it. The easiest solution (Which is also the cheapest in all likelihood) is to use an AIM-9X and shoot down the balloon, which is what they did.

"By then"-- meaning what, meaning by the time US aircraft arrive it's flown horizontally out of US airspace?  Or are you referring to a vertical limit of US airspace?  Answer could be clarified a bit--

Yes I would say by the time it flies out or above US airspace. The more likely one being flying out.

This one’s another case of “you could, but why would you want to?“
Balloons, aside from airships, are not capable of controlled flight, and that’s guidance to a target in order to capture it is going to be a problem.
Secondly, it all depends on what the interest is in capturing the device. The only reason that we wanted to get one of these things in tact is just to examine it to see what kind of capability it offered to the Chinese in the form of intelligence gathering and their spy tech (Which, if they need to use balloons to do this with in 2023, is pretty pathetic spy tech by superpower’s standards).  This examination can be done pretty well with a crashed payload unit as well, without the additional complications of having to capture it.
In the end, it just makes more sense to send a fighter airplane out there, armed with missiles or some other weapon systems, to shoot down the balloon, then salvage the remains on the ground, or in the ocean.

Nothing "pathetic" about using a balloon. Precisely the fact that it's difficult to control gives it a bit of deniability... China does have jets, but they make a lot more noise.

30 years ago the US retired a spy  aircraft capable of flying at over Mach 3 at 90,000 feet because we possessed superior means of collecting intelligence.  So, yes, if your best choice for spying is relying on unguided free balloons riding the jetstream, your spy tech IS pathetic by superpower standards!

China has plenty of spy sats. The SR-71 was retired because it could be shot down by newer SAM, and the collapsing USSR wasn't worth it. Satellites and aircraft can bring different data. Satellites fly over the land at 8 km/s, they bring one picture per area. Aircraft and balloons can film movement and deliver high resolution pictures.

And the Chinese just learned the hard way why using balloons for  reconnaissance is an outdated and stupid idea.  And it does make me wonder if they’re using that for reconnaissance purposes, how miserable there satellite reconnaissance technology is.

If satellite recon was enough for everything, UAVs wouldn't exist. Losing one balloon is hardly "the hard way" - more like testing the US response.


text:
What are the automated station types their meaning and how to determine the automated station type from a Metar report?
aviation weather documentation shows that they check for 6 automated station types.

auto_station
Indicates that the automated station type is one of the following: A01,A01A,A02,A02A,AOA,AWOS

What are the automated station types their meaning and how to determine the automated station type from a Metar report?
The following table is what I have ascertained:

auto station type
meaning
where to find in Metar report

AO1
automated station without a precipitation discriminator
there will be an AO1 after RMK

AO1A
automated station without a precipitation discriminator and manually augmented
there will be an AO1A after RMK

AO2
automated station with a precipitation discriminator
there will be an AO2 after RMK

AO2A
automated station with a precipitation discriminator and manually augmented
there will be an AO2A after RMK

AOA
?
?

AWOS
?
?

Any other automated station types?
?
?

If the station is fully automated then the qualifier AUTO will appear in the observation text immediately following the timestamp, e.g.

KHYS 031656Z AUTO 31011KT 10SM CLR 11/M02 A2967 RMK AO2 SLP056 T01061022 $

If the station is not fully automated then that qualifier will be missing:

KAPA 031653Z 11003KT 10SM BKN200 04/M01 A2970 RMK AO2 SLP065 T00441106

Note that both of the above examples used an automated system, as indicated by the AO2 remark. However, at Hays Regional Airport the system sent the observation into the NAS without any human observer input. At Centennial Airport a human observer checked the observation before it was disseminated and edited (or added) incomplete (or missing) elements.
If there is no automated station then there will be no AOn remark:

KMWA 031745Z 31014KT 10SM BKN006 BKN011 OVC022 10/10 A2892

This indicates that the observation was composed entirely "by hand."
In my experience I have never seen the remarks AO1A nor AO2A. The manual-augmentation status is indicated by the lack of an AUTO. I have also never seen AOA nor AWOS.
There is no explicit flag in the observation text or remarks to indicate whether the system is an AWOS or an ASOS, only whether or not it has a precipitation discriminator. However, there is one very big clue: a fully automated AWOS issues long-line observations three times per hour no matter what; a fully automated ASOS issues hourly METARs and occasional SPECIs as the conditions dictate.


text:
Is there a triangle representation for the Canadian airspace?
I'm looking for the following figure, except modified for Canadian airspace.
Does anybody have a copy, or can help me modify this one? I searched everywhere and could not find one.

How about this? I made it, so feel free to correct errors. I could never remember them either and the FAA triangle is amazing. I corrected the earlier triangle with a TCCA doc, and simplified.
[![enter image description here][2]][2]

I did not find a triangle representation, but this poster summarise the particularities of the Canadian airspace
https://tc.canada.ca/sites/default/files/migrated/tc_6010_airspaceposter_e.pdf


text:
Is there a way to calculate the perfect angle of incidence of a horizontal stab for a given airspeed?
I have a Grumman AA1. It’s been modified several times through stc’s to increase power and speed.  The aircraft requires full nose down trim to fly level in cruise. Is there a way to calculate the perfect angle of incidence of a horizontal stab for a given airspeed? It’s set at -3deg now, I wonder what moving it to 0deg would do? I have all kinds of load data for the horizontal stab.

Sounds like a CG problem to me, and not a stab incidence issue. Was the aircraft weighed and CG calculated after all the changes? Center of gravity range for this aircraft is as follows, according to the type certificate:(+78.5) to (+81.0) at 1500 lb.
(+77.5) to (+81.0) at 1430 lb.
(+75.0) to (+81.0) at 1245 lb.

Looking through an AA-1 maintenance manual PDF, I don't  see anything about adjusting stab incidence - it just bolts on.  Is that another STC that makes the horizontal stab adjustable, or did the engine STC (I presume you have an O-320 boat anchor on the front now) include a kit to make the stab adjustable?  Are there specs?  Just remember, when you change things outside of a published specification, you are now an experimental test pilot.

If the plane is significantly faster with roughly the same weight/CG, the stock stab angle is going to provide more downward lift, i.e. nose up, which explains why he needs more nose-down trim to compensate. Reducing the stab angle makes sense, but I have no clue how to calculate by how much, nor what that would do to low-speed handling.

I’m actually trying to work on a 337 with my IA and DER. There are people that have done this illegally with good results. There has to be a way to get some preliminary calculations.

The FSDO won't consider a 337 for this without baseline weight and balance information. You haven't answered my question or even mentioned the subject in your posts. Have you in fact done reweighing?

Yes I did do a weight and balance, everything is within limits...I agree with you that the FAA will want this as part of my data package, they actually always want it.

One clue may be increase in power and speed.  It is not unusual to trim down as plane accelerates from climb to cruise.  Since you are faster, the plane is generating more lift at a given AOA.  Greater speed will require more downtrim.  Your engine may be too powerful for your current airframe.
If the plane is safely flyable, you may try to isolate the problem by gliding power off to see if Hstab, elevator, and trim are working properly.  CG of course must be within limits.
If everything is ok, you may need a larger trim tab rather than resetting the Hstab angle.
Remember, the Hstab incidence compared to the wing AOA is critical.  I would not mess
with it.
If the problem isolates to the new engine, you may also check the thrust line.  A few degrees can make a big difference.  Your more powerful engine may need to be mounted with more downthrust.  That, and a larger trim tab, may do it.
I would definitely seek out people who have done similar modifications for expert advice.
Please, be safe.

Thank you for your input. I will not mess with the horizontal stab...you make sense. I like your idea about downthrust...just do clarify, increasing downthrust would be shimming so the motor is pointing downwards, at a negative angle in relationship to the fuselage right?

Yes, more down thrust angle will pull nose down at higher power setting but PLEASE get expert help and do it a little at a time.  I was worried that changing Hstab will give you less pitch authority, making it harder to pull out of a dive.  In the immortal words of my instructor "don't wanna do THAT".  Again, try the glide.  Pitch down and see if nose comes up strongly.  If it does, double check CG and trim tab. If it does not, you may have good shot at it with more down thrust. Good luck!


text:
Can anyone identify this jet?
I took the picture in 2011 at McCarran.

It's an F-18 Hornet:

Source: Wikipedia
Here is a view a little closer to your angle:

Source: Wikipedia
The one in your picture has extended range fuel tanks under the wings, the one above shows the hardpoint mounting for those fuel tanks.

Thank you! I was leaning toward F/A-18, but the picture made the tail and wing meld into one another on the left side of the photo which threw me off.


text:
Will a non-certified GPS source work the same in ADS-B mandated airspace?
What happens if you use a non-WAAS GPS position source in ADS-B mandated airspace? Doesn't it work the same, except for the positional accuracy?

Are you asking about non-certified, or non-waas? Those are two very different things...

Welcome to aviation.SE! I'm not sure what you're asking here and if there's even any answer. Are you asking if you could use a non-WAAS GPS unit as a position source for an ADS/B out unit? If so, are you asking if it's possible technically or legally? If legally, in which country? And if you're new to the site, the [tour] may be helpful.

Related : https://aviation.stackexchange.com/questions/29798/can-i-use-my-non-waas-gps-receiver-with-ads-b-in-the-united-states?rq=1

It may work. It may not work. Nobody knows. If you use a non-certify equipment when you are required to use the certified one you are breaking the law. Nobody can be sure your equipment will work as required but everybody are sure you are breaking the law.
Don't do it. You are endangering your life and others.


text:
Would ground effect and FOD ingestion be factors at high speeds close to the ground?
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?

At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...

If an airplane could not fly close to the ground, it could never land - duh!  If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator.  (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)

The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.

How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?

Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.

Might want to compare SilkAir Flight 185 (even though that particular case is disputed).

@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").


text:
Why does a Boeing 747-8 take more runway length to take off, compared to an Airbus A380?
The Airbus A380 is the largest passenger airliner. That also includes the Boeing 747-8. Meaning, the Boeing 747-8 is smaller than the Airbus A380. As far as I know, smaller planes use less runway length to take off, compared to bigger planes. So, the Boeing 747-8 should consume less runway length than the Airbus A380 to take off, right?
I went to Google, and searched how much runway length is required for a Boeing 747 to take off. The top result showed 3040 m. I then searched how much runway length is required for an Airbus A380 to take off. The top result showed 2900 m.
How is this possible?

The Airbus A380 is the largest commercial airliner in the world, but is not the largest of "all the planes" ... for that see Antonov A-255

"smaller planes use less runway length to take off, compared to bigger planes" not absolutely true. The very small F104 (17m long, 6 m wide) needs 1.4 km of runway to take off. The avro RJ100 (30m long, 26m wide) needs1.2 km of runway.
And the RJ100 weights 4 times the F104, but it has only 3 times the thrust (ea. engine provides 30kN, while the single engine in the F104 provides 44kN, 65 kN with afterburner)

@CGCampbell that very much depends on which metric you use - the H-4 Hercules for example has a larger wingspan than the AN-225.

This table compares some relevant numbers for the two aircraft:

Aircraft
Airbus A380
Boeing 747-8i

MTOW
575 000 kg
447 700 kg

Wing Area
845 m²
554 m²

Wing Loading
680 kg/m²
808 kg/m²

Thrust
4x 348 kN
4x 296 kN

Thrust / Weight
2.42 N/kg
2.64 N/kg

(All values from Wikipedia (A380, 747-8), all at MTOW, standard sea level conditions)
As you can see, the 747-8 has a slightly higher thrust to weight ratio (about 9% higher), which means it can accelerate a bit faster (at MTOW). However, the A380's wing is much larger resulting in a smaller wing loading (about 14% lower) at MTOW. This results in a lower takeoff speed and therefore reduces the required runway for takeoff.
If you want to compare the takeoff distances at different takeoff weights, I recommend to look at the Airport Planning Documents. These will contain graphs like these:

(Airbus Aircraft Characteristics document for the A380, ISA conditions, Trent 900 engines)

(Boeing Airplane Characteristics for Airport Planning document for the 747-8)
The second graph shows that at MTOW the 747-8 requires a little over 3000 m of runway for takeoff (at sea level). At the same weight (about 448 t), the A380 only requires about 1750 m according to the first chart. This is because it has a much lower wing loading of only 530 kg/m² now. With a 3000 m runway, the A380 can lift off at over 570 t, more than 100 t heavier than the 747-8.

This is key: lower wing loading means lower liftoff speed.

Since the existing version of the A380 is the one with the short fuselage, the "real" A380 would have a higher wing loading and, consequently, a higher takeoff distance. Pity it never went into production but hampered the version which did with a too large wing.

Then remove some wing surface area, preferably on the ends where it impedes access and flow at airports.

@Harper-ReinstateMonica then you have a plane that can access existing airports, but it needs a 7.5 km runway :)

And the two have similar displacement (?). When I start adding too much wing in KSP I can't get up to speed.

@Mazura I'm not sure what you mean by "displacement". Maybe you are referring to coefficient of drag $c_D$? According to this Wikipedia table the A380 has a lower $c_D$ than the 747. However, the value strongly depends on angle of attack, so I'm not sure how comparable these numbers are...

More wing and a lower coefficient? That's cheating.

@Harper-ReinstateMonica Redesigning a wing is a ridiculously major undertaking, which is why they developed only the one wing with room for future 'stretch' variants built in from the beginning. There's absolutely no way that there would be enough of a market for an A380 with shorter wings to justify the development cost. They don't even have enough demand to justify the continued production of the existing one.


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Can you identify this low-wing, single engine aircraft?
Can any one please identify this monoplane with a huge curved exhaust.

I still think OP was mis-identifying the curved roll-over structure as being a gigantic exhaust pipe, with the black material of the cockpit "coaming" (rim) being mistaken for the open end of the pipe!

Many thanks to you all  for taking the time to answer ther question - much appreciated.

I believe this is a Junkers T29, or something similar. This photo from behind shows that the plane has both a rollbar over the cockpit as well as a separate exhaust pipe that sticks up prominently from the engine. Image Source

Wikipedia says the curved thing is a  “longitudinal arch over their heads to protect them like a roll bar”   https://en.wikipedia.org/wiki/Junkers_T_29

Only two were built. More photos of the Junkers T29 here: https://www-airwar-ru.translate.goog/enc/other1/jut29.html?_x_tr_sch=http&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp

The T29 was also a test platform for the doppelflugel, which is that funky double-wing control surface. Nice catch.

@MikeSowsun Nice find. This photo appears to be the same as the one in the OP, albeit in better quality

What were they doing with this plane that made them decide to add a roll bar?  Were upside-down landings something they had to worry about a lot in those days?

@DarrelHoffman: It's not hard to imagine an airplane of this configuration nosing over on landing and ending up on its back, especially when used in a training role.

@FredLarson : it was an experimental aircraft after all, designed to test a completely new type of control surface which has never been used before. The first flight must have really been exciting, not even knowing for sure if the aircraft will be controllable at all.

One might expect the exhaust to be contaminated with unburned fuel and sparks and soot.  Odd that it exits right before the windscreen, also risking carbon monoxide in the cabin.  Wonder if that's why it has the aircraft ID of the beast :)


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What is the difference between equilibrium and steady flight?
If I'm flying a regular Cessna 172 and its perfectly trimmed and flying in circles holding the same altitude, is the aircraft in equilibrium? Or steady flight?
(The definition of equilibrium flight condition occurs when the sum of all forces and moments about the center of gravity is zero)
I would appreciate the clarification.

Equilibrium means all forces sum to zero. Per Newton's law $\sum F=ma$ this means that the total acceleration is also zero.
In a steady turn, the flightpath is constantly changing from a straight line. There is a centripetal acceleration that is nonzero: a continuous acceleration perpendicular to the direction of movement.
Working through Newton's law the other way round, this means that the sum of forces cannot be zero. Therefore, an aircraft in a steady-state turn is not experiencing a force equilibrium.

thank you! what if it would be a steady level flight would that be in equilibrium or not nesseceraly?

lastly, I think this would clarify any doubts I might have.... is a straight and level flight moving with a constant velocity in equilibrium ??? (not necessarily? could not be in equilibrium if the speed is constant? should I assume that if its moving with constant speed at level straight flight the sum of Lift, Weight, Drag and Thrust should be zero?)

Unaccelerated flight is always due to equilibrium of forces. That means level flight but also a steady climb or descent. Only if the flight path direction changes, or if velocity changes, you will have forces not in equilibrium.

@Sanchises i think that steady climb should not be considered an equilibrium, since, by definition, the lift is larger that the weight of the aircraft

@Grigoris No no no no no. If that were the case you would keep accelerating upwards at an increasing velocity. In fact, lift is smaller than weight in a climb due to thrust carrying part of the weight. See https://aviation.stackexchange.com/q/40921/4108 Regardless of the exact magnitude and definition of lift, weight, drag and thrust, they must sum to zero if we are not to keep accelerating.


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Is an aircraft maintenance diploma under EASA recognized for studying in the US?
I have a diploma certificate of aircraft maintenance engineering but I studied under EASA. So can I study and take the Bachelor degree in the USA without restarting all my study?

This question is unclear. Which Bachelor's degree are you intending to seek in the US?


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Can anyone identify this 1920's era biplane bomber?
What is the aircraft in this photo?  My great uncle is in the back row second to the right. He was born in 1900, so I think this photo is from around 1920. I think he was based at Kelly Field in San Antonio, TX. Does anyone know more about the aircraft or the group in the photo?

Maybe a De Havilland DH-4 variant based on how the struts protrude from the body. Particularly this image https://i.sstatic.net/g4856.jpg. For other references, check out https://en.wikipedia.org/wiki/Airco_DH.4 or https://airandspace.si.edu/collection-objects/de-havilland-dh-4/nasm_A19190051000 or https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/197397/de-havilland-dh-4/

I keep envisioning the bombardier holding that in his lap and heaving it over the side at the right point. Probably not the way it was done, though.

Next ASE question-- could the bomb on the photo really be carried by that plane?  Looks a bit oversized!

The close proximity between the pilot cockpit (the front cockpit) and the observer-gunner cockpit (the rear cockpit) suggests a Airco/ De Haviland DH-9A.  On the related DH-4, the two cockpits were much further apart, with a fuel tank in between them.
Addendum-- "1,538 DH-4s were modified in 1919-1923 to DH-4Bs by moving the pilot's seat back and the now unpressurized gas tank forward, correcting the most serious problems in the DH-4 design."  -from the National Museum of the United States Air Force website (link previously shared by ASE contributor JonSG).  Since the DH-9A was not widely used in the US, the aircraft is in fact most likely a DH-4B.


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Do pusher propellers create the same yawing moment as puller propellers?
We know that the effect of P-factor on puller propellers is the yawing moment in the opposite direction. I mean if we had a load (thrust or lift) on the right side of propeller, then the airplane will yaw to the left.
Now my question is: what about pusher propellers? Is it the same scenario or is the direction of load and resulting yaw the same? I mean in pusher propellers the right load causes right yaw?
What about pitch motion?

Welcome to Aviation Stack Exchange.  Please take the [tour] and read over the [FAQ] to get a better idea how this site works.

because when aircraft nose turns left , aircraft tail turns right

so when we deal with a pusher propeller then left load on the propeller causes right turning of the tail and left yawibg of the nose

Does this answer your question? How do I calculate propeller effects on pitching moment?

Related question showing an effect that pusher propellers do NOT have:  https://aviation.stackexchange.com/questions/29564/why-does-the-spiraling-slipstream-from-a-propeller-hit-the-left-side-of-the-fin?rq=1

Initially I thought your question was poorly worded but now I think you actually do mean what you are asking but in a sort of nonsensical way because I think you have misunderstood something.
You might be misunderstanding what P-factor actually is. It is a yawing action produced by a propeller when it is tilted so the airflow through it is not perpendicular to the disc. The most extreme example of this is on a helicopter where when it flies forward, the blades on one side move  almost directly into the wind while the blades on the other side move almost directly with the wind. A so-called advancing and retreating blade which causes asymmetrical lift production. We don't call this P-factor on helicopters though.
On an airplane, the tilt is caused by the fact that airplanes need to fly at a non-zero AOA to produce left which tilts the propeller so that it the wind isn't flowing straight through the discs of the propeller vertically. The blade on the advancing side experiences both a higher airspeed and AOA and while the blade on the retreating side experiences less and so there is assymetrical thrust produced in the propeller which tries to yaw. If an airplane is flying with zero AOA, then the air is flowing straight through the propeller disc perpendicularly and produces no yaw due to P-factor.
That means this phrase here is wrong and poorly worded

"We know that the effect of P-factor on puller propellers is the yawing moment in the opposite direction."

Opposite direction of what? Because as far as the propeller is concerned there are only two directions: forward/reverse or CW/CCW. What you mean is that the plane yaws to the left for right handed propellers with positive AOA (or various other combinations).
So from that description it should be evident there isn't a difference in P-factor between tractors and pushers.
However, P-factor isn't the only propeller effect that causes yaw. Propeller swirl pushes asymmetrically on on vertical stabilizers which are not symmetrical (i.e. above and below) which also produces a yaw. But this isn't part of P-factor. This yawing effect exists regardless the AOA.
ADDENUM: Due to gyroscopic precession, this effect causes a helicopter to pitch upward rather than roll (resulting movement is 90 degrees after the location the force where the force is applied around the disc). However, P-factor is often said to cause yaw on airplanes where the upward pitching is never mentioned. The physics don't change so I am not sure why this is.
The only think I can think of is that both pitching due to advancing/retreating blades as well yawing due to swirling slipstream pushing on an symmetrical vertical stabilizer are both always present. But on an airplane the yawing is much more noticeable whereas on a helicopter the pitching is much more noticeable (probably because on a helicopter you are already fighting the yaw due to rotor counter torque and on an airplane you are have very stable pitch control).

@FreeMan Errrr yeah. Tractors and pushers.


text:
Trailing edge tapered and leading edge straight
It is true that a wing with a straight leading edge and a tapered trailing edge has good stall characteristics?. That is, we can assure that when it enters stall, it will first be at the root and then at the tip. The most similar information I can find is with wings with sweep from the roots and the rectangular, but I don't know if that specific type works similarly.

Re "The most similar information I can find is with wings with sweep from the roots and the blocks" -- what do you mean by "the blocks"?

"we can assure that when it enters stall, it will first be at the root and then at the tip" -- This is what washout is for.

While sweeping a wing can change the shape of the load distribution and the pattern of stall (inboard vs. outboard), the amount of sweep you get by holding a high aspect ratio wing like this straight at the LE vs. c/4 vs. TE is pretty insignificant (about 3.5 deg.) and is not an effective way of changing the stall characteristics.
Instead, on a high aspect ratio wing, you would use washout and taper to tailor the load distribution and stall behavior.  This wing has a reasonable amount of taper, and will need some washout to push the stall inboard a bit.


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Why does the taxiway parallel to Runway 18 at Frankfurt Airport exist?
I was looking at these two questions about the single direction takeoff-only runway 18 at Frankfurt Airport (EDDF) when I noticed that it has a full-length taxiway (taxiway Y5) to its east.
As far as I could tell based on online sources, this runway was always designed to be used in its current southbound takeoff-only configuration. Thus the only situation I could imagine this taxiway being useful is in the case of a rejected takeoff. I couldn't find good information on the internet about the frequency of rejected takeoffs in commercial aircraft, but intuitively it seems they can't be common enough for a whole taxiway to be dedicated them. If turning around after a rejected takeoff is a concern, why couldn't the runway include a runway turnaround area at the south end?

One rather implausible reason I could think of is that the designers wanted an area for the brakes to cool down on an aircraft after a high speed rejected takeoff without having the aircraft occupying the runway during that time, but high speed rejected takeoffs are so rare that I find this very unlikely.
Even if that is the case, the combination of the southernmost part of taxiway Y5 and taxiway Y9 (the short northwest-southeast taxiway near the south end of runway 18 connecting it to taxiway Y5) makes for an adequately large "brake cooling area". After the brakes are cool, the aircraft can backtrack north along the runway, occupying it for a few minutes at most, and making the long northern part of taxiway Y5 seem unnecessary.
If that is not the case, why does taxiway Y9 exist at all? I find the existence of taxiway Y9 even more confusing than the existence of Y5, as the only case I could think of that leads to taxiway Y9 being used is when an aircraft wants to backtrack northward along runway 18, either by reaching the south end of the runway, exiting via taxiway Y5, and reentering the runway via taxiway Y9, or almost reaching the south end of runway 18, exiting via taxiway Y9, and reentering the south end of runway 18 facing northward via taxiway Y5.
The only closely analogous setup to runway 18 at EDDF that I could find is runway 11 at ZUTF in Chengdu, China. (I'd be interested to see more examples, but such things are hard to look for on the internet.) It has a parallel taxiway (taxiway K) to its north. Some sources give the runway numbering as 11/29 but inspection of aerial imagery confirms that the 29 side does not have a painted number, and there are no landing-related markings at all in either direction, so overall it closely resembles the situation at EDDF.
However, taxiway K is in this case connected to runway 11 at around the midpoint and at the far end (I couldn't find a publicly available airport diagram that shows the numbers of these connecting exit taxiways). Looking on aerial imagery, one can see that these exits are marked "NO ENTRY" in the direction of entering the runway and taxiway K itself is marked "NO ENTRY" past the third entry into the runway counting from the west. This seems to align with the theory that this taxiway is only used in a rejected takeoff.

So basically my question is, what are these taxiways actually for? If they are for rejected takeoffs, how often do the get used for that purpose and how is it worth constructing a whole taxiway just to make handling this rather uncommon event slightly more efficient? And specifically for the EDDF example, what's the reasoning behind the weird configuration of taxiways at the southern end?
Edit: I went through historical aerial imagery a bit and saw that in some interval from around 2019-2020 to around 2021-2022, the main northern part of taxiway Y5 was closed. In that case, taxiway Y9 would indeed serve as part of an "enlarged" turnaround area, together with the southernmost part of taxiway Y5, to allow aircraft to backtrack along the runway. But the aerial imagery shows that taxiway Y9 (historically called taxiway Y7) had existed since at least 2000, so this closure of taxiway Y5 can't be the reason it was put in. But is it possible that potential closures of taxiway Y5 was anticipated as a possibility long ago and they put in Y7/Y9 for redundancy?


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Are there any commercial flights that require passengers to use supplemental oxygen?
In the United States, Part 121 operations can apparently can be conducted with cabin altitudes above 15,000 ft as long as all passengers are provided with supplemental oxygen when the cabin altitude is actually above 15,000 ft  (source:  121.327 and 121.329). The requirements around supplemental oxygen for crew are stricter, but they don't really matter for this question.
For EASA, the rules for commercial operations seem to require supplemental oxygen for all passengers above 15,000 ft in pressurized aircraft and 13,000 ft in unpressurized aircraft (source: CAT.IDE.A.235 and CAT.IDE.A.240, please point out if these are not the correct sources as I'm unfamiliar with how EASA rules are structured).
However, I could not find an example of these rules being used to operate commercial flights at high altitudes in unpressurized aircraft, or in aircraft only pressurized to a very high cabin altitude.
Are there any commercial flights worldwide where, during normal operations, passengers need to use supplemental oxygen? If not, are such flights prohibited by some other rule(s)?

It's common for skydiving flights to high altitudes. For scheduled passenger flights it's wildly uneconomical.
It's much cheaper, more comfortable to passengers, and safer to fly a pressurized airplane than it is to build, maintain, supply, and sanitize suitable oxygen delivery systems for every individual passenger.


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Why do lavatories in modern planes still have ash trays?
Last week I flew on a modern B737-700. I noticed that the lavatory was equipped with ashtrays  (both on the inside as on the outside) even with the smoking sign on it. Smoking on airplanes has been banned from quite some time now, so why are lavatories still built where ash trays are provided?

Because in the US (where Boeings are made) it's required by law. 14 CFR 25.853(g) says:

(g) Regardless of whether smoking is allowed in any other part of the
  airplane, lavatories must have self-contained, removable ashtrays
  located conspicuously on or near the entry side of each lavatory door,
  except that one ashtray may serve more than one lavatory door if the
  ashtray can be seen readily from the cabin side of each lavatory
  served.

The law may be different in other jurisdictions, of course. Why the law still exists is another question, but either no one found the time to change it (laws are often very difficult to change once passed) or it was a deliberate decision to keep requiring ashtrays in case someone tries to smoke anyway.
EDIT: As commenters have noted, the law I quoted requires ashtrays outside the lavatories but it's still common to find them inside. My guess here is that the ones outside comply with the letter of the law, whereas the ones inside comply with the intent, i.e. they're there because if someone does light up, it will be inside the lavatory and not outside in plain view. This 2012 article quotes an anonymous FAA source as saying that people continue to smoke on aircraft so it still makes sense to have them for safety reasons. That raises the question (again) of why the law doesn't fully reflect reality, but that's neither unusual nor unique to aviation.

I'm sure it's a deliberate decision. Suppose some idiot tries to smoke in the lavatory, despite all the signs and warnings. The alarm goes off. They panic. If there's an ashtray, they can safely stub out their cigarette and dispose of it without causing any further danger to the plane. If there's no ashtray, they're going to stub it out on something random and dispose of it somewhere random, possibly in the bin full of paper towels, setting the whole plane on fire.

The answer to why could be revenue generation when chain smokers see an ashtray in a confined lavatory.

@Farhan - The fine for smoking on a plane (or tampering with smoke detectors) is no more than $5000. A lot for one person, but not even a millionth of the Federal budget. Even multiplied by 1,000 offenders a year all paying the maximum fine it wouldn't even fund the ATC system for a day. This sounds much more like an oversight in evolving FAA regs than an attempt to make money for the fed.gov or anyone else.

It's for safety.  Smoking may be prohibited, but if a passenger smokes anyway, you don't want the remains of the cigarette to start a fire due to improper disposal, as probably happened with Varig Flight 820:

A possible cause of the fire was that the lavatory waste bin contents caught fire after a still lit cigarette was thrown into it, the FAA issued AD 74-08-09 requiring "installation of placards prohibiting smoking in the lavatory and disposal of cigarettes in the lavatory waste receptacles; establishment of a procedure to announce to airplane occupants that smoking is prohibited in the lavatories; installation of ashtrays at certain locations; and repetitive inspections to ensure that lavatory waste receptacle doors operate correctly".

Here is the latest revision of FAA Airworthiness Directive 74-08-09.

"One size fits all".  Since smoking is/may be allowed on some foreign airlines, it would be silly for Boeing and other manufacturers to build airliners that were smoker-equipped and those for non-smoking. It is easier and less costly to install ashtrays on all aircraft and just keep the no smoking light on for those flights where smoking is prohibited.

I have flown on an embraer 195 where the no-smoking sign was replaced by a no-electronics sign.

Where was that? very interesting

This would make sense if they didn't modify about every non-structural element to the customers wishes anyway. Airline ordering new aircraft can select hundreds of options from often several types of engines over many different cabin layouts and furnishing to some changes in cockpit layout (they are cutting down on the last as is causes trouble to second-hand owners who often end up with different layouts across their fleet).

@testerMenTester It was on a KLM flight from Zurich to Amsterdam. But I belief it is on all KLM embraer models.

I've seen no-smoking signs replaced by no-electronics signs too. Unfortunately I don't remember exactly where, but it was either on a B737/A320 on a domestic flight in India, or an Emirates B777/A380.


text:
Is it practical to become an airline pilot in order to travel internationally?
I am a person with very diverse interests and a lot of life goals I want to achieve. One of them is becoming an airline pilot (just working as one for a year or two) and the other is traveling the world.
I would like to combine two goals in one, that is becoming an airline pilot after I finish college and travelling the world at the same time, i.e. flying intercontinental flights.
So, my question is basically this: Is it possible to learn to fly and become an airline pilot within about 3 years (let's say age 20-23), then immediately get employed as an airline pilot and fly intercontinental routes (even as a co-pilot)?

All the long haul commercial pilots I know spent upwards of 6 years flying small craft, instructing, taking low paid jobs at small flying clubs and working their way up through local and regional airlines, to eventually reaching flight crew on long haul international carriers. The answer is going to be a big No unless you have some incredible source of funds to make this happen!

becoming an airline pilot (just working as one for a year or two) - you're going to spend a large amount of money and spend many years training and progressing to do something for a year or two?  To answer your question, no.  It takes around 10 years to even get into the right hand seat of international flights.

+1, since after all this is a valid question, that deserves a good answer for future searches and reference.

Now it could be interesting to understand what is the life of long haul crew members, and whether they have time to visit the country they land in during their legal rest time.

Do you know for sure that you aren't affected by airsickness? A friend of mine grew up with the idea of becoming a (military) pilot, chose to study in a highschool 1 hour away in bus for this reason, worked hard to enter Italian aviation... only to find out in the first three months of training that he simply couldn't handle flying an aircraft (yes he did fly on aircrafts before, but not as a pilot). He ended up becoming an aereonautical engineer. (btw dyslexic too... so even from highschool he had to put a huge effort in all of this).

The only thing that can get you to travel internationally with minimal preparation is to be drafted for a war, but that has OBVIOUS risks.  Anything safe that takes you all over the world has checks and balances to prevent exactly this type of abuse (using a job to travel).

If you only want to be a pilot for one or two years, it is probably best to remove it of your bucket list and use the money you save by not investing in pilot training to travel the world.

@Nelson I taught English for a couple of years.  It is another way to travel internationally.  I am sure there are others.

To add to the list of alternatives, consider working on a cruise ship. It's a lot of work, but it's also kind of a non-stop party. You meet a lot of people, see some cool places, and it's generally great weather!

Interestingly, since you're a college student, studying is one viable way to travel. But it's not easy because the competition is fierce (there are more students than there are opportunities). A lot of countries have organisations that offer scholarships (or even the government itself). That would be the first thing to research. If that's not available then some universities also offer scholarships for foreign students. Finally, at the doctorate level, some research programs offer scholarship/sponsorships.

https://www.youtube.com/watch?v=WJk9Skxyi84

If you have a lot of diverse interests, I suggest picking one that has good, well-paid career prospects. Work at becoming really and well qualified at that one. Do the rest as hobbies. Earn enough money, and you can travel internationally, with time to see the places you visit.

If your goal is traveling the world, go teach English abroad. I know a few who did this - traveling abroad for several years, living in different countries gives you a "homebase" away from home to more easily explore the world. Many countries worldwide want people to do this.

If you don't get sea sick and don't have visible tattoos, come down to Fort Lauderdale and get a job on a private yacht. The yachts come here for refits between seasons. You can make $15 an hour cash cleaning bilges. If they like you they will offer to take you with them. If it is four stripes that you want, you can go training schools between seasons in the Med and Caribbean to take the licensing tests. Don't tell anyone you are not fully committed.

Have you considered joining the air force or navy? (The navy has pilots too.) You get all the flying and travel and the training is free. The downside is people shooting at you, of course.

If I had asked this question it would have been closed for being opinion-based.

No, this is not a good idea, and No, it is not possible finish your education at 23, and then get employed as an intercontinental airline pilot.
It seems you have a distorted idea of what an airline pilot actually does. An intercontinental airline pilot usually spends just 24 hours at the layover destination. Much of that time is spent sleeping to recover from the fatigue of the long haul flight and sleeping to prepare for the next long haul flight. Not much time for sight-seeing.
The first requirement for becoming an airline pilot is a love of aviation and aircraft.  Most airline pilots today have been passionate about aviation since an early age.
You will never be successful unless you are passionate about aviation due to all the roadblocks and hardships you will have to overcome in order to reach your goal.
To say that you only want to do it for 1-2 years is proof enough that you don't have what it takes.

Lets also mention that for the first 1-2 years of your career, you're probably running a short shuttle route in the midwest.  No big jets, no international destintions.

@abelenky Not every aviation career is in the USA, you know.

@DavidRicherby or a given nation's equivalent of the boring midwest

@tac Well, most nations aren't big enough to have an equivalent of the boring Midwest. For example, in Europe, surely most commercial passenger pilots have to be on international flights. The countries aren't big enough to have a lot of internal flights and your one-hour Chicago to Omaha flight turns into a one-hour London to Frankfurt flight.

@DavidRicherby has a point. The percentage of domestic flights in the U.S. is quite unique to the U.S. That said, intra-Europe flights are mostly analogous to U.S. domestic flights, except that they do technically cross international borders (even if they might remain within the Schengen zone and not require immigration.) That said, there are some airlines that fly almost exclusively long-haul international, but these are mostly in Asia (e.g. Korean Air, Asiana, Cathay Pacific.) If you want a fast-track to long-haul intercontinental, you'd probably need to move there.

If you think there's no boring destinations in Europe, you've never been to the "airports" served by low-cost carriers like Ryanair. Look e.g. where their "Frankfurt" Hahn airport is located.

It's worth pointing out that as a pilot, he will benefit from staff travel. While initially he may only be deployed on short flights, or may only have 24 hours on a layover, if he flies for a major airline he will be able to travel on the airlines long-haul flights for little more than the cost of taxes. This would allow him to travel the world for next to nothing on his days off.

Any employee of an airline gets "staff travel". You don't need to be a pilot.  Staff travel may get you to the destination relatively cheaply but you still have expenses once you arrive.  Many airline employees prefer purchasing airline tickets rather than be subject to the uncertainties of standby staff travel.

@reirab There are hundreds of domestic flights within the UK.  It's not much different to the mid-West except most of the flights are shorter.  London-Aberdeen for example is a longer flight than Paris, Brussels, Amsterdam and dozens of other international destinations.  FOs spend most of their early years on domestic.

@Simon Yes, I'm aware of that, but it's nothing like the percentage (or quantity) in the U.S., which was all I was saying on that point. About 80% of airline passengers carried in the U.S. are on domestic flights. The percentage of domestic flights is probably 90%+. The percentage of long-haul is tiny. Most airline pilots in the U.S. spend their entire career on domestic. My point was just that if you want a fast-track to flying long-haul, you'll need to go somewhere else, like SE Asia or maybe the Middle East, where a much higher percentage of flights are long-haul.

@reirab got it.  Cheers.

Even once you get a job as a commercial pilot, you're not going to be starting intercontinental routes immediately.
For starters (in the US at least), you're probably only going to be able to start at a regional airline, flying short regional jet flights back and forth.
The airline industry is very much dependent on seniority, so you'll have to put in substantial time at that regional carrier before you have a chance at even getting hired by one of the big mainline airlines. Even once you do, the routes you fly on are bid based on seniority, so you're not going to get intercontinental routes for quite a while.
Also, don't forget that intercontinental flights are flown on different equipment than medium range mainline flights, which are different equipment from regional jets. you're going to have to get trained and certified for several different aircraft along the way.
So yes, if you become a pilot you may eventually be able to fly intercontinental routes and see the world, but it will likely take decades of work before you're in that position.

In the U.S., this is very true. You'll rarely see a young pilot flying intercontinental routes for U.S. carriers. That said, it's not true for the whole world. If you get a job at Cathay Pacific, for example, you'll be flying wide-bodies almost immediately.

Also, judging from a few aspiring airline pilots I've known, your first years may not be with airlines at all, but with freight companies doing runs between small towns to pick up & deliver for FexEx & UPS.   (In piston twins, or even singles.)

If your intention is to travel the world, then don't be a pilot. Instead, be a flight attendant.
In addition to the possibility of being on international flights relatively early in your career, you will likely be surrounded by a majority of female coworkers who will be very glad to let you walk the aisles, lift the luggage, calm the rowdy passengers, and deal with the occasional butt-pincher.

Another tip is to work as a freight pilot. Airline pilots fly a small number of routes. The trips freight pilots make are much more diverse.

Hmm... At least for the case of the U.S., my understanding was that FAs had similar seniority situations to pilots, where it is mostly quite senior FAs on long-haul routes with junior FAs mostly stuck on regional routes. FAs also don't have the "move to Southeast Asia" fast-track option like pilots, unless perhaps they also happen to be young, attractive, and female.

@reirab Had a friend get picked up as a flight attendant by Hawaiian Airlines a few years back and he was telling stories of adventures in Southeast Asia early on. No college, no experience either.

@digitgopher Ah, yeah, I suppose Hawaiian would be an exception, since they have a much higher percentage of long-haul routes than other U.S. airlines (because nearly everything is long-haul from Hawaii, except the other Hawaiian islands.)

"...a year or two"? Seriously don't even think about it. But ignoring your lack of commitment, here are some ideas.
Instead of traveling the world, try living and working in a foreign country. This can be an incredible adventure and broaden your horizons. You'll have an understanding and appreciation for international concerns that can't be matched by merely being a tourist. You might still want to travel so you can use that place as a base to visit various destinations on your time off.
Southeast Asia has experienced tremendous growth in the last few years. Some of the biggest airplane orders are coming from there. Indonesia and Malaysia are looking for good pilots. Don't know if they provide training or not. Check out AirAsia and other regional airlines. Regional in this case means the Southeast Asia region and may be international.
Or the middle-east. Here's Etihad training program
This suggests Etihad accepts non-residents for training.

The comments suggest that Etihad no longer accepts foreigners

Judging from the pilots I've had when flying with them (and what I've heard from others,) Cathay Pacific heavily recruits Western pilots. Every pilot I've had with them was American, British, or Australian, even though the airline is based in Hong Kong.

Is it possible to learn to fly and become an airline pilot within
  about 3 years (let's say age 20-23), then immediately get employed as
  an airline pilot and fly intercontinental routes (even as a co-pilot)?

Yes, but not in the US. You'll have to look overseas at airlines like Emirates/Qatar etc. for that.

Airline routes are offered by seniority; and pilots that have been with the airline a significant amount of years (I am talking 5+ at minimum) are given the longer routes.
In the US, where I have the most exposure to the flight training side - once you get your ATP (Airline Transport Pilot) and have acquired all the relevant type certifications - your entire purpose in life is to build up your hours as PIC (Pilot In Command) / PF (Pilot Flying).
You will be doing this on regional airlines, which may be contracted out to larger airlines. You may be flying an aircraft that's painted in United colors, but its actually a regional airline used on "feeder" routes to the larger hub airports. This is typically the case in the US (and Europe).
Or, you may be employed by an airline that has no international routes.
Outside of these areas - if you come to the Middle East, you may be flying international routes at the start of your career; simply because that's the only option - and you may be flying the long haul jets if that's all the airline has to offer.
For example, Emirates (the largest operator of 777 and the A380) flies international exclusively; and the majority of their routes are medium to long haul (greater than 3 hours flight time). You may have a chance to fly internationally, but on shorter routes like Dubai - Muscat, Dubai - Bahrain, Dubai - Kuwait (this is the shortest A380 flight by Emirates, and is used for crew training/familiarization).
Qatar Airways is similar - they use their short routes for crew familiarization and training on their newer aircraft. They flew their 777-200/300LR on the Doha - Kuwait - Doha circuit when they first got the aircraft (a route normally served by the A320); and the 787 on the Doha - Dubai - Doha circuit (again, normally served by the A320).
However, you may not have the opportunity to fly the longer routes until well into your career with the airline; and you will be starting off (training) in smaller aircraft and a lot of simulator time.
Typical training period for commercial pilots is between 3 and 4 years (if you are directly trained by an airline, such as Emirate's flight training program) and then you are qualified as an airline pilot.

Actually, Southwest flies to Mexico, Jamaica, the Dominican Republic and Costa Rica, Belize, the Bahamas and Aruba. See their map.

@BurhanKhalid Yeah, international routes are a somewhat recent addition for Southwest. Many of them were added after they acquired AirTran Airlines, which already flew several routes to the Caribbean. Southwest doesn't have any long-haul, flights, though, as they only operate 737s.

How feasible is it to work on Middle Eastern routes with Emerates for people who don't speak Arabic?

Seems like the hard way to see the world.
Assuming you have a private license with complex and retractable endorsements. Then the next step is to get your instrument rating, multi engine, turbine and commercial ATR rating and at least 800 to a thousand hours as PIC (Pilot in Command). By now you have spend over $50,000 and might be employable as first officer for a small low budget commuter line at a couple of G's a month.
Is it worth it? That's up to you. I have over 4,000 hours in single and multi engine prop and jet aircraft. I own and fly a Beech Baron which is considered to be one of the more challenging light twin engine planes. I do not consider myself qualified to be an airline pilot.


text:
Can you become a CFI with only a PPL (EASA)?
In Europe, can you get your CFI rating with a PPL only or do you need a CPL?
I assume that if you get paid to do flight instruction it's considered a commercial activity, so you'll need a CPL. But what if you do instruction without getting paid, do you still need a commercial licence to be a CFI?

The EASA requirements for a CFI ticket are:

Over 18 yo
Hold a Commercial Pilot License or a Private Pilot License with the CPL theory done.
A minimum flight experience of 200 hours as a Pilot of which 150 will be as Pilot in Command
Hold a Medical Certificate Class I or II in accordance with
the license


text:
What can trigger the ELT on GA aircraft?
Does the Emergency Locator Transmitter (ELT) on smaller aircraft activate automatically in case of an accident? If so, what triggers it? Is it a certain amount of G's that triggers it or are there other parameters taken into account?

Striking the ELT smartly  against one of the aircraft tires is a great way to set it off. That is one of the best ways to test the ELT for its annual ops check.

I managed to activate an ELT the first time I landed a 210.  I call it "landing with authourity."  It was the first time I had landed a single engine piston plane in years.  Flared a bit high...

There are four different types of ELTs:

Automatic fixed ELT (ELT(AF)). An automatically activated ELT which is permanently attached to an aircraft.
Automatic portable ELT (ELT(AP)). An automatically activated ELT which is rigidly attached to an aircraft but readily removable from
the aircraft.
Automatic deployable ELT (ELT(AD)). An ELT which is rigidly attached to an aircraft and which is automatically deployed and
activated by impact, and, in some cases, also by hydrostatic sensors.
Manual deployment capability is also provided.
Survival ELT (ELT(S)). An ELT which is removable from an aircraft, stowed so as to facilitate its ready use in an emergency,
and manually activated by survivors.

All the aircraft I fly in (all two of 'em) have the third type. If the aircraft is submerged or experiences a high G-force, the ELT will be triggered. There's also a button on the panel to activate it manually.
I'm not sure what G-forces are required to set off the ELT, but they must be fairly significant—I've slammed my plane down pretty hard while misjudging my landings, and never had it go off.
According to https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91-44A.pdf:

To meet the "g" force requirements of TSO-C91, automatic fixed-type inertially activated ELT's (except overwater type) must activate at any inertial force, parallel to the longitudinal axis of the aircraft when installed in accordance with the manufacturer's instructions, of 5(+2, -0)g and greater for a time duration of 11 (+5, -0) milliseconds or longer.

So, there you have it. You need 5–7 Gs for 11–16 milliseconds—but only in the direction the plane is pointing. Misjudging your landing flare and stalling the plane 20 feet off the runway won't set it off, as that's not on the axis they're measuring.

ELTs can also be turned ON or off manually at the device.

I know some can; is it possible with all of them? Of the four types I listed here, two of them specifically mention that they can be triggered manually.

@Aquarello The Automatic deployable ELTs that are in general aviation aircraft have a switch for ARMED and ON. ON is used for testing them at annual and after battery replacement. Many (most?) also have an OFF position so they aren’t accidentally triggered during maintenance. Some of them have a switch on the panel that will turn them on.

@jscarry Note that the annual testing requirements also include a requirement to test the crash sensors, etc. So while turning the switch to "ON" for testing is fine, it is not sufficient.

@JonathanWalters Never heard of that requirement, but you are correct, it is in 91.207. If I am reading the manual correctly, the listening for the sweeps when the unit is switched to ON is all you need to do. From the ACK website, "Model E-01 Emergency Locator Transmitter
The model E-01 ELT must be inspected yearly to insure continued airworthiness. The procedures as described in section 7 (Periodic Maintenance) of the installation and operation manual part number E-01-M (all revision dates) should be followed.
These tests also fulfill the requirements of FAR 91.207."

@JonathanWalters I’ve done around 30 annuals and we never tested the crash sensors. It turns out that there is a procedure for it. AC 43.13-1B. "A TSO-C91 ELT can be activated by using a quick rap with the palm. A TSO-C91a ELT can be activated by using a rapid forward (throwing) motion coupled by a rapid reversing action. Verify that the ELT can be activated using a watt meter, the airplane’s VHF radio communications receiver tuned to 121.5 MHz, or other means (see NOTE 1). Insure that the “G” switch has been reset if applicable."

@JScarry Yes, the requirement is found in §91.207. It is not a requirement of the aircraft annual (§43 App D), but of the ELT inspection required every 12 calendar months.

There is another way that an aircraft ELT (or for that matter, any ELT) can be set off: By a mechanical or electronic failure of the unit. This is usually caused by corrosion and is more common on maritime ELTs than on ELTs designed for aviation use. Believe me ... it is more common than you might think. As a USCG pilot, I have many times located an active ELT that did not appear to be activated by any of the previously mentioned methods. If your ELT mysteriously activates (especially if that activation is intermittent), consider that possibility. We once flew over 800 miles to a large freighter where the ELT appeared to have been deliberately activated (i.e., manually turned on) only to have the surprised crew discover the ELT safely untouched in its bracket. They were impressed that we came that far to see if they were okay; we had left Shemya Island in the Aleutians in the middle of the night and just wanted to go back to sleep.

I believe that it is a requirement that the ELT transmitters have an ON switch on the transmitter housing.  I don't have a cite, but I might be able to dig it out.  There is a similar requirement for marine emergency beacons.


text:
What is the quickest way to get an airship rating?
I already have private pilot for single engine land with instrument and commercial ratings.

Which country are you in?

AOPA: What it takes to become a blimp pilot

@Pondlife I reside in NJ, USA  and my base airport is 47N

Since you didn't specify the type of Airship you're looking to get a rating in, I found a Flight Standardization Board (FSB) Report for a Zeppelin, that discusses the training required for that specific Airship.
Here is the relevant time requirements for this particular airship from the document:
5.2 Commercial Airship Pilot
(a) Ab Initio:
Standard duration of training: Approximately 20 months
Maximum duration of training: 24 months
Theoretical training: 300 hours
Practical training: Three months on a ground crew
Minimum of 50 training flight hours
Minimum of 150 supervised flight hours

(b) Students holding a CPL:
Standard duration of training: Approximately 15 months
Maximum duration of training: N/A
Theoretical training: Minimum of 93 hours
Practical training: Three months on a ground crew
Minimum of 40 training flight hours
Minimum of 130 supervised flight hours

(c) Type Rating:
Standard duration of training: Approximately four months
Maximum duration of training: N/A
Theoretical training: Minimum of 49 hours
Practical training: Minimum of 25 training flight hours
Minimum of 100 supervised flight hours

The Commercial Practical Test Standards for Lighter-than-Air can be found on the FAA Website, and you would need to make sure that you had satisfied the following conditions:

An applicant already holding a commercial pilot certificate who
  applies for an additional category and/or class rating on that
  certificate must:

hold a commercial pilot certificate;
have the prescribed aeronautical experience and training required for the category and class rating sought;
pass an additional knowledge test for the rating sought (unless already rated in airplane, rotorcraft, or airship) since the beginning
  of the 24th month before the month in which he/she takes the practical
  test; and
obtain an endorsement from an authorized instructor certifying that the applicant has been given flight instruction in the applicable
  AREAS OF OPERATION listed in 14 CFR part 61, section 61.127, for the
  commercial pilot rating sought in preparation for the practical test
  within 60 days preceding the date of application. The statement shall
  also state that the instructor finds the applicant competent to pass
  the practical test, and that the applicant has satisfactory knowledge
  of the subject area(s) in which a deficiency was indicated on the
  knowledge test report.

So you can see the standard duration of training is approximately 15 months. There are some interesting anecdotes in this article from AOPA:

Pilots interested in getting their pilot certificate with an airship
  rating will have to train while on the job, since there are no schools
  that teach this particular skill, according to Bret Viets, chief pilot
  on the MetLife Snoopy Two blimp.

Veits goes on to say that it took him 66 days. (He started Dec 4, 2007 and took his checkride on Feb 8, 2008). And he thought he did in a pretty short time period. It sounds like he got lucky and ended up having the airship to himself for training for a couple weeks!
Looks like you're on your way with a commercial rating, too:

The company prefers that applicants have a commercial rating, whether
  it’s on airplanes, helicopters, gliders, or hot air balloons, said
  Viets. “It just makes the transition to airship hourly requirements
  less if someone already has a commercial rating,” he said. “To
  transition to airships is a minimum of 50 hours, but it usually takes
  a little longer than that, like any aircraft rating.”
If an applicant does not have a commercial rating, he or she will need
  250 hours in airships before getting that commercial airship rating,
  said Viets. “They prefer pilots with 1,200 hours and a CFI
  certificate,” he said.

Another (more recent) anecdote: Embry-Riddle's Alumni Magazine Lift had a feature in the Fall 2017 Edition (https://lift.erau.edu/flying-into-the-wind/) where an Alumnus mentioned that it took him 9 months to earn his Airship rating.


text:
What kind of container should be used for storing a disassembled Cessna 172?
I need to store a damaged aircraft away rather than leave it exposed to the weather and elements on a tie-down at an airport. It is a Cessna 172. If I remove the wings and horizontal stabilizer (from the tail), I can fit all lengthwise into a 40 foot shipping container.
However the span of the landing gear is just over 8 feet and won't allow fitting width-wise into a standard container. I suppose the landing gear can also be removed, but not desirable. Are there extra-wide containers suitable for storing small aircraft?

How long of storage, and what kind of local weather are you facing? - Those details may impact people's answers. Also whether or not you can build a temp structure, or if it has to be some kind of Container like portable box.

@TheLuckless We are in the mid-Atlantic northeast so we are frequented by noreasters, snow, rain, hail, and the occasional hurricane (Sandy).  We have heavy bird and insect infestation, not to mention scavengers and theives.  My beacon is missing.  It will cost much money to repair the aircraft and make it airworthy again.  In the meantime, I figured a shipping container would shelter the aircraft and I can also put on a flatbed truck and transport to wherever location.  I am sure I am not exceptional in having this need.  Don't they have extra wide containers?

If it is just over 8 feet, you could try removing the tires.  And put it on some little dollies or something.

If the search for a wider container comes up dry, would it be possible to build a cradle that can hold the fuselage with enough roll on it to make the gear fit diagonally in the container?  If my math is right, there's something like 11' on the diagonal.

@0tyranny0poverty The point of having standard shipping containers is that they are standard. The height can vary within a certain range, but if the length* or width varied, they couldn't be stacked. (*Okay, there are two lengths, but one is exactly twice the other, so they're still stackable.)

Have you looked at the sort of shrink-wrap plastic that I see used for winter storage of boats?

Be sure to check whether "cost of storage + cost of repair" < "cost of selling as-is + cost of buying a replacement".  Sometimes the cheapest way to store a vehicle is to sell it then buy a new one later.

A "dry van" (nonrefrigerated) 53 foot trailer, commonly towed as a "tractor trailer" sports an extra 3 inches of inside diameter (8 foot 3 inches) to go with 9 feet 3 inches in height.
You could also build a custom crate either onsite (storage shed) or portable (on a flatbed).
Transporting it to a local barn or unused building is also possible, better than leaving it to the elements.
I would look into local storage options, with the wing removed, there should be many.

Finding a barn is better choice as it has a lot of space in it. You need an escort traffic police to close certain roads in order to tow the plane on a flat bed trailer truck to the barn. However, bear in mind, the cost of renting the barn is key to keeping it there. Otherwise, if it can sold away, you might as well do it, too. There is no point having a non-functional plane when it could be sold to another interested party for the safekeeping of it.


text:
Can I get my IFR practical and oral examinations directly through the FAA if I can't find designated examiner?
A friend  needs to go for instrument and commercial check rides and can't find designated examiner that is local.  Can she schedule one at the nearest FAA office?

Why doesn't she ask them?

Is there any question how to find designated examiner?

@Simon closed at this time.

In theory it's possible to contact the local FSDO and ask for a checkride with an FAA inspector, and it's free (see here, here, here). But personally I've never heard of anyone doing it and I can't even find anything on the FAA's website about it.
The FAA's statistics show that in 2016 there were 34,156 initial checkrides with DPEs but only 465 with FAA inspectors (two thirds of those were for ATP), so it's very unusual. That file also shows pass rates by DPE vs. inspector, by the way, and despite some online horror stories it looks like the pass rates were broadly similar.
FWIW, it's fairly common for candidates to travel/fly several hours to a DPE (see the FAA's locator tool), either because there isn't one available locally or because they want to use the 'right' one. I don't know what your friend considers "local" and how far away she's already looked, but she may want to just look further away. Of course flying somewhere adds some costs but if she's doing IR/CPL then it's probably a relatively minor cost compared to what's she already spent on training and it's another excuse to fly (if she needs one!).


text:
How can I calculate the effect of winglets on aircraft performance?
For a project at university I am having to produce a SIMULINK model of a Nimrod MR2 aircraft. The next step is to increase the endurance of aircraft and a possible route for this is adding winglets to the tips of the wing to increase the efficiency of the wing. However I am struggling to calculate the effect this will have on the performance of the aircraft.
Could anyone offer some help on this topic please?

You should be specific about what you need help with. Remember that StackExchange is not a forum, it's a question/answer site. Please let us know what you are stuck on.

you can start by having a look here: https://aviation.stackexchange.com/questions/8556

I need to know how a winglet device will affect the lift and drag produced by the aerofoil? Is there a formula to calculate this?

the airfoil is a section of the wing, its characteristics do not change. what matters is the vehicle in its ensemble.

I think Peter Kämpf's answer on the question Federico linked probably answers your question. Peter's not a big fan of winglets and he makes a good case as to how wing extensions are more effective. But all the math is there

Basically, there are two ways. One is easy but imprecise, and the other is hard but more precise.
First the easy one: Look at other aircraft and estimate how much winglets affect lift and drag. Make sure to do this at several lift coefficients; winglets help much more at high lift coefficients. Don't forget to account for the added mass of the winglets and their added friction over their surface area. Bonus points for estimating losses due to sideslip.
The hard way is to do a numerical simulation of the wing. Since you want to know what difference the winglets make, you can focus on a comparison between a regular and a winglet-equipped wing and transfer the effect to the full airplane. For the lift and induced drag effects, you will at least need to divide the wing into panels and simultaneously solve the Biot-Savart equations for bound vortices at the quarter chord of each panel plus the trailing free vortices with control points at the three-quarter point where local flow must be parallel with local wing inclination. Make sure you use a method which does better than to assume that all panels lie in one plane!
I have no experience with Simulink - I guess there are libraries around for vortex lattice or even Euler codes, but if you are free to choose your tools, maybe it is worth to take a look at XFLR5. This should work out of the box for your project, and all you need to add is a proper input file.


text:
What are the names of these aircraft?
I need help to identify a group of planes, can someone help me?

NC248V was registered as a Fairchild KR-135 (http://www.airhistory.org.uk/gy/reg_N32.html) but that doesnt look right.

@Jamiec Looks like the model builder ran out of "V" decals, so he flipped an "A" upside down. :/

The top image is a Bellanca Skyrocket.

The second image looks like the Fairchild FC-1, one was built as a prototype, followed by the FC-2 which was powered by a radial engine.

Not sure about the last, found a few similar but nothing exact.

The top one looks different from the Bellanca Skyrocket picture: different angle of vertical tail, different rudder, different engine cowling shape.

@Koyovis there are a few different models of the Skyrocket, the cowling and tail do have differences

Here is a better picture of an XRE-3 Skyrocket (civilian name CH-400). The tail and the wing struts match a lot better. The one in the question sports a NACA cowling and indicates a late series model.


text:
What are the two turning tendencies that occur during a steep turn?
A question has come up in preparation for a Block exam. what are the two turning tendencies that occur during steep turn? If you know this may you please explain to me, why these tendencies occur.
Cheers !

"The two turning tendencies"? During a steep turn, the aircraft's track tends to rotate into the turn, the heading tends to rotate along with the track but lag behind it, the pitch tends to decrease (which is to say, the nose tends to go down), and the bank angle tends to get steeper. All four of those tendencies involve a kind of "turning", so I can only guess which two of the four are "the two turning tendencies".

Thank you for your reply

There are two:  the overbankong tendency as a result of the outboard wing moving faster through the air and generating more lift than the inboard  wing.  The second is the left turning tendency as a result of P-factor, engine torque and spiral slipstream effects on the tailboom and vertical fin, requiring more right rudder to maintain a coordinated turn to the right than to the left.

This second effect has nothing to do with turns. It demands more right rudder (on most aircraft) even in a straight flight. The effect may marginally increase during the turn due to higher AoA and RPM, but it's still the same effect.

Actually at high angles of attack it will be very noticeable.  You will require considerably more right rudder to coordinate a steep turn.

@757toga That is incorrect. The engine crankshaft is permanently oriented relative to the  longitudinal axis of the airplane.   The angle between this and the relative wind varies with angle of attack.  Consequently P factor varies as well.   P factor is going to be a function of propeller angle of attack and engine power settings, and not whether the airplane is in level flight or not.

No, that’s incorrect again.  Manufactures will do things like preset the alignment of engines on the airframe etc. to reduce the effects of P factor, torque, spiral slipstream, etc as much as possible, but it cannot cover all conditions perfectly, including straight and level flight, without additional use of rudder, which is why larger, more powerful twins are equipped with rudder trim.

Consider what happens in slow flight.   You will have a great deal of left turning tendency in this regime and require quite a bit of right rudder to track a straight, even in straight and level flight.  Again aeronautical designers trying design an aircraft it offers a good performance characteristics in the majority of flight regimes, but compromises and trade off do have to be made

@757toga is right with regards to P-factor specifically. Remember the left-turning tendency comes from two major very different aerodynamic effects (plus a few minor ones and mechanical torque): P-factor arises when prop axis is not aligned with the wind (airspeed) (and yes, the core reason is blade speed difference), and spiral slipstream is always present when the prop is turning. Now, in most cases, even at low speed, the latter prevails over P-factor. In cruise, with prop nearly aligned with airflow, P-factor is totally negligible. But again, all that is not related to turn (the maneuver).

Left turning tendency is a combination of P-Factor, torque and spiral slipstream.


text:
Can I log any PIC time if my medical certificate is out of date and I haven't flown in 20 years?
I haven't flown in 20 years. My medical certificate is not up to date. Can I log a fam flight with a local instructor?

This topic comes up frequently, and the answer (in the US at least) is always the same. If you are rated in the category and class of aircraft you are flying then you can log PIC time for the time you are the sole manipulator of the controls regardless of your Flight Review status, currency of your medical, or whether you are flying with an instructor or a friend. Unless you are current you cannot act as PIC but you can log PIC time.

Which country or regulations are you asking about?

To answer your question, specific to the US, you may log your fam flight with a CFI as dual received, and also as PIC for the time you are the sole manipulator of the controls (which will likely be the entire flight).
You don't need a medical to log PIC, but you will likely need one to act as PIC, depending upon what you are flying.
But for training, you clearly can log time as PIC when you are the sole manipulator of the controls, in a class and category for which you are rated.
Have fun!

I find it hilarious that one can log PIC without fulfilling the requirement to act as PIC.

@kevin, yes, the “PIC” in log is somewhat a misnomer, because it is closer to PF (but not exactly PF either).

Depending on jurisdiction and aircraft you might be able to. The FAA's recent third class medical reform may allow you to fly if your medical stretched into the last decade

Under the reforms, pilots who have held a valid medical certificate
  any time in the decade prior to July 15, 2016, may not need to take
  another FAA medical exam. The 10-year lookback period applies to both
  regular and special issuance medicals.

and long as your biannual is current and you did not lose your medical for a medical reason (lapsing is not considered a loss). All that being said you can log PIC time if you comply with the above listed things. You will need at least a biannual review so instructor time will have to happen. If you have not flown in 20 years some training is well worth your time before brining any passengers along.

This is all relevant and useful, but it doesn't answer the question about logging time


text:
Why use jet engines instead of propellers when designing new airplanes?
I'm looking at the 100 people project and I am looking at clean airplanes. Why did we stop using a clean source of lift, the propeller?

Turbofans (B737/A320) are basically large propellers, so we continue with propellers optimized for M 0.8 speed, and also continue with traditional propellers for slower aircraft flying at lower altitude (e.g. ATR, or Q400). For propellers, the actual source of energy is often a turboprop, that is a (jet fuel) turbine, like other airliners. This is not cleaner in any way.

Unless you're talking about a rotary-wing craft (i.e. helicopter), I don't really think the propeller creates lift - it's the airflow around (and most specifically below) the wing that creates lift. Also, in what way do you think it is a "clean source" of lift where a jet engine is (by inference) a "dirty source" of lift?

How are propellers cleaner than jet engines?

Look into Propulsive efficiency (and maybe also this one).  Turboprops have a speed of peak efficiency, which is around mach 0.6 or so.  If you try to go faster, it gets significantly less efficient.  A high bypass turbofan, on the other hand, is most efficient at a higher speed, maybe mach 0.8 - 0.85.  So the simple answer is: we switched from props to jets because people wanted to fly faster but didn't want to burn a lot of extra fuel to do that.